Visible light communication (VLC) is not new, but its advantages, such as large amounts of free-to-use spectrum and capability to support very high data rates, make it an emerging and promising concept in solving problems on wireless (5G and 6G) and IoT smart systems.
The usage of light-emitting diodes (LEDs) is evident in almost every aspect of our daily lives because they offer lower power consumption and cost, smaller size and longer lifespan. Because of this, VLC has attracted worldwide research that impacts how it can be developed and fulfill massive connectivity opportunities.
In the future, light and radio communication waves will complement each other. Marcos Katz, a prominent research professor, has gone on record saying that today’s global penetration of LEDs is close to 50% and that it will reach 90% by 2030. This creates a massive potential for VLC, which is a subset of optical wireless communication technologies.
By implementing a hybrid VLC-radio communication system, when the light has been obstructed by the receiver, the system will automatically switch to a radio mode seamlessly.
We can draw from common scenarios. For example, in a hospital, in order to reduce possible interference to sensitive equipment, the use of light would be maximized, while in an office, which requires high data rate support most of the time, both radio and light can be used in unison.
VLC is an attractive alternative to radio frequency (RF) signals for high data rate transmission and limitless broadband solutions. It has therefore seen an upsurge in research, both on the current state of VLC and its improvements going forward.
VLC blends illumination and optical communication and offers enormous business potential in return. It complies with the national strategy for energy efficiency and emissions reduction, and it enables the creation and technological advancement of access networks and next-generation communication networks.
Why VLC Is Suitable for IoT
VLC transmits data using LEDs to send wireless communications signals. This innovation can be used as a standalone technology or as a supplement to cellular networks and has potential applications, particularly for indoor environments.
Without a doubt, VLC can enable new pervasive wireless systems in the context of the Internet of Things (IoT). Researchers have demonstrated a new visible light communication system — based on devices called multiple quantum well (MQW) III-nitride diodes — that uses a single optical path to create a multi-channel communication link over the air. This can be used as a backup communication link for IoT devices.
VLC is capable of serving devices in indoor environments because of its low cost due to the use of the existing lighting infrastructure. Moreover, it has a high-speed transmission with an abundant, license-free visible light spectrum and guaranteed security, as these types of signals cannot penetrate walls.
For object tracking and navigation, there is high-accuracy localization via visible light positioning (VLP). Energy harvesting from visible light also extends battery life for power-constrained devices. Densely deployed LEDs can be transformed into access points (APs) to support indoor IoT devices.
Utilizing LEDs can provide massive connectivity for various types of IoT communications, including machine-to-machine, vehicle-to-infrastructure, infrastructure-to-vehicle, chip-to-chip and device-to-device.
In its entirety, VLC can be applied to most IoT-based smart systems. An example of this is indoor navigation and art gallery monitoring, where an array of LEDs on the ceiling of stores and museums act as a source of illumination to transmit the location of certain products and artworks to a user's mobile device.
Another area of application is vehicular VLC, where the LED headlights and taillights of modern cars have been used in automobile collision prevention systems. In healthcare, VLC-IoT can be applied to transmit medical data through biomedical sensing and data transmission.
Visible Light for 5G and 6G
VLC has attracted attention and is considered a supplementary way for future 5G wireless communications due to the shortage of RF bandwidths in traditional wireless communications. VLC can also be used in sensitive scenarios, such as on aircraft and in manufacturing plants.
Designers of 5G and 6G networks can maximize VLC in support of heterogeneous networks, with a much higher data rate and more robust security. It is envisioned that 6G will integrate air, space and underwater networks with terrestrial networks, though this will present the additional challenge of higher data rates.
Conventional wireless communication techniques cannot address the challenges alone. Thus, the integration of technology such as VLC, whose frequency range of operation lies in the range of 400–800 THz, could work best. This is far greater than conventional radio frequency bandwidths.
With extensive research being carried out on the suitability of VLC for numerous applications, this technology could be one of the frontrunners in playing a larger role in 5G, 6G and beyond.
This wireless version of fiber optics could be a game-changer for connectivity speed, coverage and reliability.
Human Factor
VLC’s unique advantages include high security and privacy, no electromagnetic compatibility issues and support for high-data rates. These can come in handy in the particularly challenging research parameters of communications through biological tissues.
Katz’s team of researchers has demonstrated how light can be used to convey data to and from in-body devices such as implants. Near-infrared light has been used to transmit data across biological tissues. This medical innovation is yet to become mainstream, as more studies on the short- and long-term implications must be conducted.
Some have also proposed the use of light for very short links (in the range of a few millimeters) for deeply implanted devices as well as between in-body devices. As researchers plan to compare radio and optical communications in biotissues, more extensive measurements must be done to be able to characterize biological tissues as a medium for wireless communications. If effective, this can result in a unique and highly secure light-based system that can be key to carrying out key medical ICT functions.
Additionally, a team of researchers at the University of Massachusetts Amherst has invented a low-cost, innovative way to harvest the waste energy from VLC — which can be used to power wearable devices, or even larger electronics — by using the human body as an antenna.
Scientists based in the US showed that energy harvesting through visible light communications could repurpose waste electromagnetic emissions and turn them into a power source for wearable sensors.
On the trial, humans wore copper coils fashioned into rings and bracelets to collect radio frequency noise produced by solid-state lighting. And the researchers have shown that wearing the metallic collectors amplified the amount of gathered energy tenfold (when compared with a single standalone coil).
As time progresses, VLC is bound to gain more appeal as information will be sent wirelessly by simply turning LEDs on and off.
